We were interested in identifying design of nanoparticles that will enhance their refrigeration efficiency. We focused on maximizing their quantum yield while minimizing their non-radiative processes. In particular, we developed nanocrystals with and without an inert shell. We characterized the refrigeration efficiency by monitoring the temperature of the nanocrystals optically trapped in vacuum. Overall, we saw an increase in refrigeration efficiency for the shelled nanoparticle with a minimum temperature of ~150K. We will also show works towards controlling the motional temperature of the levitated nanoparticle paving the way towards absolute cooling in levitated optomechanics.
We are interested in the optomechanical manipulation of nanodiamonds with a high concentration of SiV centers. Optical tweezers usually rely on the interaction of light and the ‘bulk’ polarizability of the nanoparticle itself. Here we exploit the polarizability of electronic resonances of optical centers embedded in the solid-state matrix to enhance the optical forces. This effect becomes particularly relevant for ensembles of active centers. The emitters being closely packed in a sub-wavelength volume, can act cooperatively, enhancing further the optical forces. We will show the optical force spectroscopy of nanodiamonds with different levels of brightness in a specifically designed optofluidic microchip. Our results open the possibility to extend the use of optical tweezers beyond current capabilities and apply the powerful toolbox of atomic physics for the quantum manipulation of ‘massive’ mesoscopic objects.
Levitated mesoscopic particles, with their intrinsic low coupling to the environment, are ideally suited as hybrid quantum platforms of mesoscopic size and mass. In vacuum, the only coupling to the environment is the levitation field itself, resulting in a mechanical oscillator with a very high-quality factor. Optically levitated systems in vacuum have recently entered the quantum realm with demonstration of cooling to the motional quantum ground state using passive and active feedback methods. The levitated particles in most of these experiments are optically inert such as SiO2 nanospheres. Here we are interested in studying and developing techniques suitable for the stable levitation of optically active nanoparticles such as rare-earth ion activated nanocrystals. In particular we will show experimental results on the laser refrigeration of levitated nanocrystals down to 150K and our efforts towards using measurement-based oscillator control for the absolute cooling of the levitated particle.
We are interested in the opto-mechanical manipulation of nanodiamonds with a high concentration of SiV centers. Optical tweezers usually rely on the interaction of light and the ‘bulk’ polarizability of the nanoparticle itself. Here we exploit the polarizability of electronic resonances of optical centers embedded in the solid-state matrix to enhance the optical forces. This effect becomes particularly relevant for ensembles of active centers. The emitters being closely packed in a sub-wavelength volume, can act cooperatively, enhancing further the optical forces. This opens the possibility to apply the powerful toolbox of atomic physics for the quantum manipulation of ‘massive’ mesoscopic objects.
We perform the experimental generation of pairs of photons on a solid-state rare-earth ion doped crystal of Eu3+:Y2SiO5, by using a DLCZ-like protocol designed for inhomogeneously broadened media. The idea relies on the use of the atomic frequency comb technique, in order to rephase the atoms for the emission of the photons. A specificity of this protocol is its high temporal multimode capacity, as many pairs of photons can be emitted at different instants in time. A Cauchy-Schwarz inequality violation of 2.88>1 is witnessed, proving the non-classical correlations of the photon pairs that we produce. A detailed analysis of the source and detection imperfections is conducted, revealing ways of increasing the quality of the pairs that are produced.
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